Although age has a lot to do with hair turning gray, some people develop this rather early. Experts have pointed out that it happens because of one's lifestyle, and below are three crucial mistakes you might be making that contribute to gray hair:

1) You're lacking vitamin B12.

A deficiency in vitamin B12 was determined as one of the reasons for graying hair, according to a study published in the National Institutes of Health. The vitamin is essential to the body's nerve functions and helps build healthy red blood cells. If you're suddenly seeing gray hair, consider filling your diet up with vitamin B12-rich foods like clams, oysters, chicken or salmon, according to the U.S. Office of Dietary Supplements.

2) You smoke.

Smoking is also one of the reasons for premature grey hair, according to a study in the British Medical Journal. The cigarette's toxins not only deplete the body of its nutrients, like vitamin B12, but they also contribute to faster aging and the development of arterial diseases. Perhaps it's time to finally quit the habit - it'll be good for your overall health and wellness.

3) You're actually stressing your hair out.

The link between stress and premature hair graying happens indirectly. Your hair won't instantly turn to salt and pepper shade if you're in a stressful situation. Rather, the cells in your body are stressed and damaged by different agents, including aging, chemicals, ultraviolet light and even radiation (for those undergoing medical treatments). Unfortunately, this is unavoidable - especially with aging - according to National Geographic. However, you can slow down the process if you use less hair dye or schedule your outdoor activities at better times of the day. You should also mind your diet and keep exercising to boost your immune system to prevent illnesses.